Chlorine is suspected as a cancer risk because it interacts with organic matters in water and in biol gical systems leading to the formation of various toxic chloroderivatives. The overall objective of this proposed study is to investigate the interaction of chlorine and/or chlorinated compounds with the cellular constituents under the physiological condition in relation to the biochemical mechanism of tumor formation as induced by this interaction. Specifically, we shall: (1) Study the effect of acute and chronic treatment of chlorinated water on the structure and function of biological membranes, (2) Evaluate the synergism and promotion on tumorigenesis when chlorine water ingestion is combined with other chemical carcinogens, and (3) Examine the inhibitory effect of dietary antioxidants on the chemical carcinogenesis as induced by chlorine and dimethylnitrosamine (DMN). The interaction of chlorine with some major body constituents of rat, such as proteins, lipids, nucleic acids and nucleotides at the cellular and subcellular level, will be investigated after administration of (32Cl)-labeled hypochlorite by intragastric intubation. The change in the compositions (lipids and proteins) and functions (membrane-bound enzymes, transport activities) of erythrocyte membranes, kidney and liver mitochondria and synaptic plasma membranes will be studied and compared bwtween control and experiment animals. The growth rate, tumor incidence and associated histological and membrane change with either chlorine or combined with DMN administration will be examined. In addition, the inhibitory effect of dietary vitamin E and selenium on the chemical carcinogenesis as induced by chlorine alone or combined with DMN will be evaluated. It is anticipated that the result of this investigation will provide more information about the prevalence of mutagenic agents in drinking water and in the biological system. Possible preventive measures to the chemical carcinogenesis may be developed as a result of this study.